Creation of SFA cutting hot cell at the Mining and Chemical Combine
Experimental Demonstration Center is being created at the Mining and Chemical Combine to adjust advanced and ecologically safe technologies for VVER-1000 SNF reprocessing. The first start-up facility was built in December 2015.
The technology of the first start-up facility of the Experimental Demonstration Center includes dismantling of fuel rods one by one from the fuel assemblies and fragmentation of the fuel rods to adjust SNF dissolving technology.
The SFA cutting hot cell with equipment (including the facility for dismantling of fuel rods from the SFA and fuel rod fragmentation facility) was designed by specialists of Sosny Company who also supervised equipment fabrication, participated in the equipment tests, provided installation support, precommissioning of the equipment at the Mining and Chemical Combine.
Fuel rod dismantling technology was not used before at the radiochemical facilities due to complexity of highly precise positioning of tools for removal of fuel rods from the SFA grid. Manual fuel rod dismantling is a very time consuming process, therefore the necessity arose to create a complex of equipment and automated systems for instrumentation and control of technological processes for dismantling of fuel rods from VVER-100 SFA.
In the fuel rod dismantling facility SFA is installed in the tilter, secured, the head and tail are cut off and then each fuel rod is dismantled from the SFA one by one. The main difficulty of the technology is to cut the bottom support grid of SFA without using lubricating or cooling liquids (in accordance with nuclear safety requirements) and without breaking tightness of the fuel rods. Fuel rod dismantling comprise of pushing and removal of each of 312 fuel rods from the SFA spacer grids. This operation requires precise positioning (up to micron) of the pusher in the axial coordinates of openings in the SFA supporting grid.
The facilities in the SFA cutting hot cell are maintained remotely by manipulators: А-1000 power manipulator and four А-100 master/slave manipulators of Wälischmiller (HWM, Germany).
Fragmentation facility cuts fuel rods into fragments of 25 - 49 mm long (up to the operator) and loads fragments into the crucible cask for subsequent technological operations (voloxidation, dissolution, etc.). The peculiarity of the fragmentation facility designed by Sosny Company is that the fragments are cut almost without crushing the fuel rod tube ends that shall result in higher quality of SNF removal from the tubes during voloxidation.
In order to specify technological parameters and optimal regimes of equipment operation the technology of SFA dismantling and fuel rod fragmentation at the first stage was adjusted using the specially fabricated mass-dimensional SFA simulator, then full-scale FA simulator with fuel rods filled with depleted uranium. The last stage of testing was performed using actual spent fuel.
The unique technology implemented at the Experimental Demonstration Center will result in significant increase of efficiency and ecological safety of SNF reprocessing.
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